Sun tanning

A visible tan line on a woman whose skin has been darkened by ultraviolet exposure, except where covered

Sun tanning or simply tanning is the process whereby skin color is darkened or tanned. It is most often a result of exposure to ultraviolet (UV) radiation from sunlight or from artificial sources, such as a tanning lamp found in indoor tanning beds. People who deliberately tan their skin by exposure to the sun engage in a passive recreational activity of sun bathing. Some people use chemical products which can produce a tanning effect without exposure to ultraviolet radiation, known as sunless tanning.

Moderate exposure to the sun contributes to the production of melanin and vitamin D by the body, but excessive exposure to ultraviolet rays has negative health effects, including sunburn and increased risk of skin cancer,[1] as well as depressed immune system function and accelerated aging of the skin. Some people tan or sunburn more easily than others. This may be the result of different skin types and natural skin color, and these may be a result of genetics.

Several cases of tanning addiction have been reported by medical researchers. Though the mechanism by which tanning addiction occurs is unknown, some evidence indicates that the release of endorphins during the tanning process causes the pleasurable effects that underlie the addiction.[2]

The term "tanning" has a cultural origin, arising from the color tan. Its origin lies in the Western culture of Europe when it became fashionable for young women to seek a less pale complexion (see Cultural history below).

Tanning process

A sun tanned arm showing browner skin where it has been exposed

Melanin is a natural pigment produced by cells called melanocytes in a process called melanogenesis. Melanocytes produce two types of melanin: pheomelanin (red) and eumelanin (very dark brown). Melanin protects the body by absorbing ultraviolet radiation. Excessive UV radiation causes sunburn along with other direct and indirect DNA damage to the skin, and the body naturally combats and seeks to repair the damage and protect the skin by creating and releasing further melanin into the skin's cells. With the production of the melanin, the skin color darkens. The tanning process can be triggered by natural sunlight or by artificial UV radiation, which can be delivered in frequencies of UVA, UVB, or a combination of both. The intensity is commonly measured by the UV Index.

Cross-sectional view showing skin tone becoming darker due to the production of more melanin to overcome the damage of melanin caused by UV radiation

There are two different mechanisms involved in production of a tan by UV exposure: Firstly, UVA radiation creates oxidative stress, which in turn oxidises existing melanin and leads to rapid darkening of the melanin. UVA may also cause melanin to be redistributed (released from melanocytes where it is already stored), but its total quantity is unchanged. Skin darkening from UVA exposure does not lead to significantly increased production of melanin or protection against sunburn.[3]

In the second process, triggered primarily by UVB, there is an increase in production of melanin (melanogenesis),[4] which is the body's reaction to direct DNA photodamage (formation of pyrimidine dimers) from UV radiation.[5] Melanogenesis leads to delayed tanning, and typically becomes visible two or three days after exposure.[4] The tan that is created by increased melanogenesis typically lasts for a few weeks or months, much longer than the tan that is caused by oxidation of existing melanin, and is also actually protective against UV skin damage and sunburn, rather than simply cosmetic. Typically, it can provide a modest Sun Protection Factor (SPF) of 3, meaning that tanned skin would tolerate up to 3 times the UV exposure as pale skin.[6] However, in order to cause true melanogenesis-tanning by means of UV exposure, some direct DNA photodamage must first be produced, and this requires UVB exposure (as present in natural sunlight, or sunlamps that produce UVB).

The ultraviolet frequencies responsible for tanning are often divided into the UVA and UVB ranges.

UVA

Ultraviolet A (UVA) radiation is in the wavelength range 320 to 400 nm. It is present more uniformly throughout the day, and throughout the year, than UVB. Most UVA is not blocked by the atmosphere's ozone layer. UVA causes the release of existing melanin from the melanocytes to combine with oxygen (oxidize) to create the actual tan color in the skin. It is blocked less than UVB by many sunscreens, but is blocked to some degree by clothing. UVA is known both to cause DNA damage and to be carcinogenic. However, it operates not by inducing direct DNA damage, but by producing reactive oxygen species which damage DNA indirectly. UVA (see above) induces a cosmetic tan but little extra melanin protection against sun damage, sun burn, or cancer.

UVB

Ultraviolet B (UVB) radiation is in the wavelength range 280 to 320 nm. Much of this band is blocked by the Earth's ozone layer, but some penetrates. UVB:

Tanning behavior of different skin colors

A person's natural skin color affects their reaction to exposure to the sun. An individual's natural skin color can vary from a dark brown to a nearly colorless pigmentation, which may appear reddish due to the blood in the skin. In 1975, Harvard dermatologist Thomas B. Fitzpatrick devised the Fitzpatrick scale which described the common tanning behavior of various skin types, as follows:[9][10]

Type Also called Sunburning Tanning behavior von Luschan scale
I Very light or pale Often Occasionally 1–5
II Light or light-skinned Usually Sometimes 6–10
III Light intermediate Rarely Usually 11–15
IV Dark intermediate Rarely Often 16–21
V Dark or "brown" type No Sometimes darkens 22–28
VI Very dark or "black" type No Naturally black-brown skin 29–36

Health aspects

The most-common risk of exposure to ultraviolet radiation is sunburn, the speed and severity of which vary among individuals. This can be alleviated at least to some extent by the prior application of a suitable-strength sunscreen, which will also hinder the tanning process due to the blocking of UV light.

Overexposure to ultraviolet radiation is known to cause skin cancer,[11] make skin age and wrinkle faster,[12] mutate DNA,[13] and impair the immune system.[14] Frequent tanning bed use triples the risk of developing melanoma, the deadliest form of skin cancer, according to a 2010 study. The study suggests that the melanoma risk is linked more closely to total exposure than it is to the age at which an individual first uses a tanning bed.[15] The International Agency for Research on Cancer places the use of tanning beds in the highest cancer risk category—along with bacon and sunshine—describing them as carcinogenic to humans, if used as recommended.

Several organizations, such as the World Health Organization (WHO), the American Cancer Society and the US Surgeon General have issued guidelines warning about sun tanning and UV radiation exposure, either from the sun or from indoor tanning.[16][17][18]

Production of vitamin D is essential for human health. Moderate exposure (avoiding sunburn) to UV radiation provides benefits such as increased vitamin D, as well as other possible benefits that are still being studied.[19]

Several tanning activators have used different forms of psoralen, which are known to be photocarcinogenic.[20][21][22] Health authorities have banned psoralen since July 1996.[23]

Cultural history

La promenade (1875) by Claude Monet. At that time in the West, the upper social class used parasols, long sleeves and hats to avoid sun tanning effects.

Tanning has gone in and out of fashion. In the United States and Western Europe before about the 1920s, tanned skin was associated with the lower classes, because they worked outdoors and were exposed to the sun. Women went to great lengths to preserve pallid skin, as a sign of their "refinement".[24]

Women's outdoor clothing styles were tailored to protect against sun exposure, with full-length sleeves, and sunbonnets and other large hats, headscarves, and parasols shielding the head. Women even went as far as to put lead-based cosmetics on their skin to artificially whiten their skin tone.[25] However, when not strictly monitored, these cosmetics caused lead poisoning. Light-skinned appearance was achieved in other ways, including the use of arsenic to whiten skin, and lightening powders. The preference for fair skin continued until the end of the Victorian era.

By the early 20th century, the therapeutic benefits of sunlight began to be recognised.[26] In 1903, Niels Finsen was awarded the Nobel Prize in Medicine for his “Finsen Light Therapy”.[27] The therapy was a cure for diseases such as lupus vulgaris and rickets. Vitamin D deficiency was found to be a cause of rickets, and exposure to the sun would allow vitamin D to be produced in a person. Therefore, sun exposure was a remedy to curing several diseases, especially rickets. In 1910 a scientific expedition went to the island of Tenerife to test the wider health benefits of "heliotherapy",[28] and by 1913 "sunbathing" was referred to as a desirable activity for the leisured class.[29]

Shortly thereafter, in the 1920s, fashion-designer Coco Chanel accidentally got sunburnt while visiting the French Riviera. When she arrived home, she arrived with a sun tan and her fans apparently liked the look and started to adopt darker skin tones themselves. Tanned skin became a trend partly because of Coco’s status and the longing for her lifestyle by other members of society. In addition, Parisians fell in love with Josephine Baker, a “caramel-skinned” singer in Paris, and idolised her dark skin. These two women were leading figures of the transformation that tanned skin underwent, in which it became perceived as fashionable, healthy, and luxurious.[30][31][32] Jean Patou capitalised on the new tanning fad, launching the first sun tan oil "Huile de Chaldee" in 1927.[33]

Just before the 1930s, sun therapy became a popularly subscribed cure for almost every ailment from simple fatigue to tuberculosis. In the 1940s, advertisements started appearing in women’s magazines which encouraged sun bathing. At the same time, swimsuits' skin coverage began decreasing, with the bikini radically changing swimsuit style after it made its appearance in 1946. In the 1950s, many people used baby oil as a method to increase tanning. The first self-tanner came about in the same decade and was known as “Man-Tan,” although it often led to undesirable orange skin.[34] Coppertone, in 1953, marketed its sunscreen with a drawing of a little blond girl and her cocker spaniel tugging on her bathing suit bottoms revealing her bare bottom and tan line; this advertisement was modified around the turn of the 21st century and now shows a little girl wearing a one-piece bathing suit or shorts.[35] In the latter part of the 1950s, silver metallic reflectors were common to enhance one’s tan.

In 1962, sunscreen commenced to be SPF rated, although SPF labeling in the US was not standardised by the FDA until 1978. In 1971, Mattel introduced Malibu Barbie, which had tanned skin, sunglasses, and her very own bottle of sun tanning lotion. In 1978, both sunscreen with an SPF 15 rating as well as tanning beds first appeared. In 2007, there were an estimated 50,000 outlets for indoor tanning; it was a five-billion-dollar industry in the United States,[36] and had spawned an auxiliary industry for indoor tanning lotions including bronzers, intensifiers, and accelerators. Since then, the indoor tanning industry has become more constrained by health regulations.[37] In China, darker skin is still considered by many to be the mark of the lower classes. As recently as 2012, in some parts of China, ski masks were becoming popular items to wear at the beach in order to protect the wearer's face from the effects of the sun.[38]

Many people regard visible tan lines as un-aesthetic, and seek to avoid tan lines that will be visible when regular clothes are worn. Some people try to achieve an all-over tan or to maximize their tan coverage. To achieve an all-over tan, tanners need to minimize the amount of clothing they wear while tanning. For women who cannot dispense with a swimsuit, they at times tan with the back strap undone while lying on the front, or removing shoulder straps, besides wearing swimsuits which cover less area than their normal clothing. Any exposure is subject to local community standards and personal choice. Some people tan in the privacy of their backyard where they can at times tan without clothes, and some countries have set aside clothing-optional swimming areas (popularly known as nude beaches), where people can tan and swim clothes-free. Some people tan topless, and others wear very brief swimwear, such as a microkini or thong.

A 1969 innovation is tan-through swimwear, which uses fabric perforated with thousands of micro holes that are nearly invisible to the naked eye, but which transmit enough sunlight to approach an all-over tan, especially if the fabric is stretched taut. Tan-through swimwear typically allows more than one-third of UV rays to pass through (equivalent to SPF 3 or less), and an application of sunscreen even to the covered area is recommended.[39][40][41]

Sunless tanning

An artificial source tanning bed

To avoid exposure to UVB and UVA rays, or in seasons without strong sunshine, some people take alternative steps to appear with darkened skin. They may use sunless tanning (also known as self-tanners); stainers which are based on dihydroxyacetone (DHA);[42] or cosmetics such as bronzers. Others may create a tanned appearance by wearing tan-colored stockings or pantyhose.

Many sunless tanning products are available in the form of darkening creams, gels, lotions, and sprays that are self-applied on the skin. There is also a professional spray-on tanning option or “tanning booth” that is offered by spas, salons, and tanning businesses.[43] Spray tanning does not involve a color being sprayed on the body, instead it uses a colorless chemical which reacts with proteins in the top layer of the skin, resulting in a brown color.

See also

References

  1. ↑ "Ultraviolet (UV) Radiation". Retrieved 27 August 2015.
  2. ↑ Tejeda Hugo A.; Bonci Antonello (2014). "Shedding "UV" Light on Endogenous Opioid Dependence". Cell. 157 (7): 1500–1501. PMID 24949960. doi:10.1016/j.cell.2014.06.009.
  3. ↑ Miyamura Y, Coelho SG, Schlenz K; et al. (February 2011). "The deceptive nature of UVA tanning versus the modest protective effects of UVB tanning on human skin". Pigment Cell. 24: 136–147. PMC 3021652 Freely accessible. PMID 20979596. doi:10.1111/j.1755-148X.2010.00764.x.
  4. 1 2 Amy Thorlin (5 February 2006). "The Tanning Process". Lookingfit.com. Retrieved 15 April 2015.
  5. 1 2 Nita Agar; Antony R. Young (2005). "Review: Melanogenesis: a photoprotective response to DNA damage?". Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis. 571 (1–2): 121–132. PMID 15748643. doi:10.1016/j.mrfmmm.2004.11.016.
  6. ↑ "The Surgeon General's Call to Action to Prevent Skin Cancer" (PDF). U.S. Department of Health and Human Services. 2014. p. 20. A UVB-induced tan provides minimal sun protection, equivalent to an SPF of about 3.
  7. ↑ John A. Parrish; Kurt F. Jaenicke; R. Rox Anderson (1982). "Erythema And Melanogenesis Action Spectra Of Normal Human Skin". Photochemistry and Photobiology. 36 (2): 187–191. PMID 7122713. doi:10.1111/j.1751-1097.1982.tb04362.x.
  8. ↑ "The known health effects of UV". WHO. 1 December 2010. Retrieved 1 August 2012.
  9. ↑ Fitzpatrick TB: Soleil et peau [Sun and skin]. Journal de Médecine Esthétique 1975; 2:33-34
  10. ↑ Weller, R; J Hunter; J Savin; M Dahl (2008). Clinical Dermatology (4th ed.). Malden, Massachusetts, USA: Blackwell Publishing. p. 268. ISBN 978-1-4051-4663-0.
  11. ↑ "Reviewed Substances". ntp.niehs.nih.gov. Retrieved 13 December 2016.
  12. ↑ Fisher GJ, Wang ZQ, Datta SC, Varani J, Kang S, Voorhees JJ (November 1997). "Pathophysiology of premature skin aging induced by ultraviolet light". N. Engl. J. Med. 337 (20): 1419–28. PMID 9358139. doi:10.1056/NEJM199711133372003.
  13. ↑ Sinha RP, Häder DP (April 2002). "UV-induced DNA damage and repair: a review". Photochem. Photobiol. Sci. 1 (4): 225–36. PMID 12661961. doi:10.1039/B201230H.
  14. ↑ Baadsgaard O (January 1991). "In vivo ultraviolet irradiation of human skin results in profound perturbation of the immune system. Relevance to ultraviolet-induced skin cancer" (PDF). Arch Dermatol. 127 (1): 99–109. PMID 1824747. doi:10.1001/archderm.1991.01680010109019.
  15. ↑ Peeples, Lynne. Study: Frequent tanning-bed use triples melanoma risk. CNN. 27 May 2010.
  16. ↑ "Sunscreens - IARC Handbook of Cancer Prevention Volume 5". www.iarc.fr. Retrieved 9 February 2017.
  17. ↑ "Skin Cancer". www.cancer.org. Retrieved 9 February 2017.
  18. ↑ General, Office of the Surgeon. "The Surgeon General’s Call to Action to Prevent Skin Cancer". www.surgeongeneral.gov. Retrieved 9 February 2017.
  19. ↑ Baggerly, Carole A.; Cuomo, Raphael E.; French, Christine B.; Garland, Cedric F.; Gorham, Edward D.; Grant, William B.; Heaney, Robert P.; Holick, Michael F.; Hollis, Bruce W.; McDonnell, Sharon L.; Pittaway, Mary; Seaton, Paul; Wagner, Carol L.; Wunsch, Alexander (22 June 2015). "Sunlight and Vitamin D: Necessary for Public Health". Journal of the American College of Nutrition. 34 (4): 359–365. PMC 4536937 Freely accessible. PMID 26098394. doi:10.1080/07315724.2015.1039866.
  20. ↑ Ashwood-Smith MJ. (1979). "Possible cancer hazard associated with 5-methoxypsoralen in sun tan preparations". BMJ. 2 (6198): 1144. doi:10.1136/bmj.2.6198.1144-b.
  21. ↑ M. J. Ashwood-Smith; G. A. Poulton; M. Barker; M. Mildenberger E (1980). "5-Methoxypsoralen, an ingredient in several sun tan preparations, has lethal, mutagenic and clastogenic properties". Nature. 285 (5): 407–409. PMID 6991953. doi:10.1038/285407a0.
  22. ↑ Zajdela F, Bisagni E (1981). "5-Methoxypsoralen, the melanogenic additive in sun-tan preparations, is tumorigenic in mice exposed to 365 nm UV radiation". Carcinogenesis. 2: 121–7. PMID 7273295. doi:10.1093/carcin/2.2.121.
  23. ↑ Autier P.; Dore J.-F.; Cesarini J.-P. (1997). "Should subjects who used psoralen sun tan activators be screened for melanoma?". Annals of Oncology. 8 (5): 435–437. PMID 9233521. doi:10.1023/A:1008205513771.
  24. ↑ Singer, Merrill; Hans Baer (28 July 2008). Killer Commodities: Public Health and the Corporate Production of Harm. AltaMira Press. p. 151. ISBN 0-7591-0979-6. Retrieved 11 September 2009. Harris investigated the history of the parasol... everywhere ordinary people were forbidden to protect themselves with such devices "pallid skin became a marker of upper-class status". At the beginning of the 20th Century, in the United States, lighter-skinned people avoided the sun. ... Tanned skin was considered lower class.
  25. ↑ Agredano, YZ; Chan, JL; Kimball, RC; Kimball, AB (February 2006). "Accessibility to air travel correlates strongly with increasing melanoma incidence". Melanoma Research. 16 (1): 77–81. PMID 16432460. doi:10.1097/01.cmr.0000195696.50390.23.
  26. ↑ "The Times". 25 August 1900: 1: An advertisement for a 'German Bath In Scotland' offers 'For Health and Pleasure...Pure Air and Sun Baths...'.
  27. ↑ "All Nobel Laureates in Physiology or Medicine". Nobel Media. Retrieved 29 April 2015.
  28. ↑ "The Times". 12 March 1910: 12.
  29. ↑ "The Times". 4 September 1913: 6.:Describing a visit by the Prince of Wales to the pretty town of Sigmaringen the reporter says: ‘The Castle possesses many delightful terraces which could be adapted for sunbathing.’
  30. ↑ Hanson, Peter G. (22 June 2009). "About Face". The Effects of Aging, Health and Stress on Your Face. FaceMaster. Archived from the original on 23 April 2012.
  31. ↑ "Sun and Clouds: The Sun in History". Magic Bullets - Chemistry vs. Cancer. The Chemical Heritage Foundation. 2001. Archived from the original on 20 June 2010. By the 1920s, the therapeutic effect of the sun was widely promoted, and two well-publicized French personalities gave "tanning" a fashion boost. Coco Chanel, of designer fame, returned to Paris after a cruise on the Duke of Westminster's yacht with a tan that became all the rage. And the natural caramel skin color of singer Josephine Baker made women all over the world try to emulate her skin tone.
  32. ↑ Koskoff, Sharon (28 May 2007). Art Deco of the Palm Beaches. Arcadia Publishing. p. 2. ISBN 0-7385-4415-9. Retrieved 11 September 2009. In 1920s France, the caramel-skinned entertainer Josephine Baker became a Parisian idol. Concurrently, fashion designer Coco Chanel was "bronzed" while cruising on a yacht. A winter tan became a symbol of the leisure class and showed you could afford to travel to exotic climates.
  33. ↑ Steele, Valerie, ed. (2010). The Berg Companion to Fashion. Berg. p. 554. ISBN 1847885632.
  34. ↑ "NTP: Report on Carcinogens (RoC)". Ntp.niehs.nih.gov. 13 February 2009. Retrieved 29 July 2009.
  35. ↑ http://www.coppertone.com/home/
  36. ↑ Wright, Dan (16 August 2007). "Working The Tan". The Daily News-Record (Harrisonburg, Virginia). Retrieved 11 September 2009. The tanning industry has grown about 25 percent over the past six years, according to the Indoor Tanning Association. In the United States, about 25,000 free-standing tanning salons employ 160,000 people and generate more than $5 billion in annual revenue, the association said.
  37. ↑ Clark, Patrick (5 October 2016). "Twilight of the Tanning Salons". Bloomberg News. Retrieved 9 October 2016.
  38. ↑ Levin, Dan (3 August 2012). "Beach Essentials in China: Flip-Flops, a Towel and a Ski Mask". New York Times. Retrieved 5 August 2012.
  39. ↑ Taylor, Angela (17 October 1969). "Tan-Through Fabric Lets Sun Shine In". The New York Times. p. 55. Retrieved 30 November 2014.
  40. ↑ "Scorecard: No nudes is good news". Sports Illustrated. 1 September 1969. Archived from the original on 12 October 2013. permits 40% of the sun's ultraviolet rays
  41. ↑ "Tan-tastic bikini that lets rays shine through". Daily Express. 30 May 2009. Retrieved 17 September 2014. 80 per cent of UV rays... a stretchy yarn described as 'a chicken wire mesh material'
  42. ↑ "Dihydroxyacetone". Retrieved 6 July 2010.
  43. ↑ "Sunless tanning: A safe alternative to sunbathing". Retrieved 6 July 2010.
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